"The Code" tells the story of a series of explosions in Kawasaki City. Terrorists placed multiple bombs on the streets, threatening the government to release political prisoners. Assisting the security forces and firefighters are the detectives of "Detective Agency 5". The mayor commissioned the agency to try to dismantle the bombs. Detective 507 is a genius at cracking codes. He cracked the codes one by one, prevented the explosions, and arrested the terrorist group. 507 received a commission from the Shanghai branch, and he was fascinated by the sequence code he had never seen in the photo. 507, eager to find out the full picture of the code, came to Shanghai. Waiting for him were detective 523 and the president. The president said that although 507 was good at cracking codes, he was not good at solving cases, so he came to support him. In fact, he had other purposes. With the help of the intelligence dealer, 507 came to a nightclub and found the client Meilan who was a singer there. Meilan was the mistress of the boss of the Qinglong Society, the largest gang in Shanghai. It is said that anyone who has anything to do with this peerless beauty will die strangely. 507 followed Meilan to her residence and sneaked into the house without the bodyguards. He told Meilan that he had come to Shanghai from Japan to decipher the code and hoped that she could show him the complete code. Meilan said, "I can show you the code, but the price is that you must free me from the mystery of the code." Meilan took off her clothes and the code turned out to be a tattoo on her back, which was tattooed by her father who had been separated from her since childhood. 507, who had recovered from the embarrassment, quickly began to decrypt and record. The guard noticed something was wrong and broke in, and 507 hurriedly fled. A mysterious man rescued 507 from the clutches of the Qinglong Society. He left a sentence "Forget the code, otherwise you will die" and then disappeared. The boss of the Qinglong Society believed that the code on Meilan's back was related to the treasure location of the old Japanese Army. He imprisoned Meilan and racked his brains to decipher the code. 507 rescued Meilan and used his genius to break the traps of the code one after another, quickly approaching the truth. Meilan's heart is gradually captured by 507...Finally, 507 finds the answer, and he and Meilan come to the cave where the treasure is hidden. The Qinglong Society is following, and the mysterious man with an unknown identity, what is the truth behind the code? !